1. Field of the Invention
The present invention relates to a stator used for a torque converter of an automatic transmission for an automotive vehicle.
2. Prior Art
Conventionally, as shown in FIGS. 5 and 6, there has been known a resin-made stator comprising an annular plate portion 2 integrally formed toward an inner peripheral direction on an end (a right end in FIG. 6) of a cylindrical portion 1 in an axial direction or an adjacent portion thereof, a desired number (four in FIG. 5) of notch portions 3 provided on an inner peripheral end portion of the plate portion 2 at equal intervals, and an annular metal fitting 4 integrally held on the inner peripheral end of the cylinder portion 1 by an insert molding.
Specifically, the annular metal fitting 4 is constituted by an outer race of a one-way clutch, and a lubricating fluid (ATF) flows in the inner peripheral end of the stator as shown by an arrow in FIG. 6 in order that the one-way clutch smoothly operates. The notch portion 3 provided on the inner peripheral end portion of the plate portion 2 serves to guide the flow of the lubricating fluid, and is provided in such a manner that the notch portion 3 extends through the plate portion 2 in a thickness direction thereof (an axial direction) as shown in the drawing.
However, in the above stator, since the notch portion 3 is provided in a manner so as to extend through the plate portion 2 in the thickness direction thereof as mentioned above, the inner peripheral end portion of the plate portion 2 forms "a discontinuing portion" which does not continue in a circumferential direction. Accordingly, the following disadvantage is caused by the above structure.
Accordingly, the plate portion 2 is deformed immediately after the stator is molded or by a shrinkage of the resin under a high temperature atmosphere condition. Particularly, as a result that the inner peripheral end portion of the plate portion 2 is discontinuous in the circumferential direction, the plate portion 2 is deformed in such a manner that an angle in an opening of the notch portion 3 becomes large. Therefore, due to this deformation, a tensile stress to the circumferential direction as shown by an arrow in FIG. 5 is applied around the notch portion 3, so that a crack 5 may be generated in the plate portion 2.